I own a 1997 Saturn SC1 with manual transmission and about 145K miles on it. Overall, it’s a sweetheart of a car with few problems. The last couple of years, though, I’ve noticed that the engine will start to run louder and a bit rougher, and when I check the oil, it’s extremely low. Pouring in oil fixes it, for a while. These days, I’d say I’m adding about a quart of oil every six weeks. I pretty much only get an oil change for the filter.
The thing is, there are no oil stains where I park the car. There is also no blue smoke from the tail pipe. If it’s not leaking and not burning, where is the oil going? Is my car breaking the Law of Conservation of Mass? Should I notify NASA?
Bonus questions:
what’s the likeliest cause of disappearing oil?
considering that any big repair is probably going to cost more than the car is worth, but that keeping the car running at least one more year would be very helpful, what can I, a complete car schlub, do to best deal with this problem?
about how much life do you figure my little Rocket Venus has left?
when I can replace her, knowing that her Blue Book value will be pocket change, should I donate her to a charity, give her to a deserving person, or drop her off at a scrap yard? Highest priority would be environmental responsibility, second priority helping a good cause, third would be the unlikely possibility of profit.
About how many miles are you getting out of a quart of oil? It takes a pretty large consumption problem before you actually start to see visible smoke, especially on cars with catalytic converters (one of my cars burns a quart every 600 and doesn’t smoke). Also, believe it or not, a quart every 1,000 miles is “normal” according to most car makers, so if it’s less than that don’t worry about it too much.
The most likely cause of oil burning is just a plain old worn out engine (rings to be specific). 145k miles should be way too soon for a modern car, but frankly, if you let the oil get so low that it started to affect how the engine was running, I’m going to step out on a limb and suggest that this car probably hasn’t seen the best maintenance.
The one “fingers crossed, worth a try” thing you can do is change the PCV valve. I’ve never actually seen it fix an oil consumption problem, but apparently it can happen and for a little $5 part you can change yourself it’s worth a try. It could also be something on the top end like worn valve stem seals which would be cheaper than rings, but is still probably pushing what it sounds like you want to spend on this car. It might be a good idea to price out the valve stem job and see if you’re willing to invest that much in the car to see if you should pay someone to actually diagnose the engine internals.
As for how to nurse it along, that depends on exactly how much oil you’re burning. My rule of thumb is that if it takes longer to go through a quart of oil than it does a tank of gas, just keep topping off the oil. Buy it in bulk. If it’s burning so fast you’re having trouble keeping it full, you can start thinking about pouring in those miracle engine restore additives and running heavier weight oils to try to delay the inevitable.
The good news is that if the consumption rate isn’t getting precipitously worse, you can nurse an oil burner for a long, long time provided you don’t let it run out of oil-- my aforementioned oil burner has been burning a quart every 600 for the last 40,000 miles and still runs great (and, let’s see… 67 quarts of oil, at $3/qt is only about 200 bucks-- still a long way from breaking even on a ring job!). You do still need to change the oil on time, since the contaminants in the oil don’t get burnt off with the oil-- if anything you’ll want to change the oil more frequently since the worn rings are also letting more combustion gasses into the crankcase. You may also need to unfoul the plugs from time to time and don’t be suprised if the catalytic converter dies a premature death.
If there are no visible leaks then I suggest general engine wear with that mileage. Maybe the maintenance has not been the greatest over its life. You might also have a small leak that occurs only while moving so you don’t see the oil, but I believe general wear. That engine could go on an awful long time. Depending on climate conditions, I would use 10-30W oil and half a can of STP. Also, I would keep the oil topped off every half a quart. You are doing serious damage every time you let it get low enough that you hear it. You have certainly added much to the wear by doing this. It was not frugal for you.
PS. You don’t see the smoke because the converter is so hot that it burns the oil off before it shows out the pipe. The downside is that the oil will damage the oxygen sensors more quickly so expect the check engine light to trigger soon. This is why adding a little STP might help cut the consumption and fogging of the O2 sensors and converter.
Yes, the maintenance has, at times, been lackadaisical, more from lack of funds and symptoms of ADD than any willing negligence. I will check the oil at every fill up from here on out. I go through about a tank of gas a week, with mpg ranging from 25 in the city all the way to 34 for road trips. So, figure about 1600 miles per quart of oil.
The oxygen sensors may already be damaged. My car has a habit of lighting up the “check engine” indicator randomly. I had thought it might be some sort of short, as it seems to happen when there’s been a warm day followed by a chilly morning. The light stays on for the next 4-5 starts and then disappears until the next time. Knowing that shorts in the electrical system can be next to impossible to track down and seeing as how all the mechanics around me charge $50-80 for a diagnosis, I’ve let it go.
The good news is, I now have use of another car, so Rocket Venus will get a lot less use from me, hopefully lasting longer. Also, the catalytic converter was replaced about two and a half years ago.
So, just to recap:
switch to a heavier oil. Current specs say 5W-30. You guys recommend anywhere from 10W-30 to 20W-50.
keep adding oil, and never let it get so low I can hear a difference in the engine. Also, change the oil more frequently.
add half a can of STP.
consider changing the PVC valve, valve stem seals, or rings in that order.
New questions:
what do the numbers on oil mean? I knew once, and those brain cells died.
where does the STP go, in the oil or in the gas?
There was a third question, but I can’t remember it. Ah, well. Another time.
Geasy Jack’s suggestion w/regard to PCV valve is a good one and most likely the only possibility other than major/impractical repairs. Not so sure about valve guides/seals. Unless I am mistaken you’d see exhaust smoke on deceleration.
Regardless, buy cheap/heavy weight oil. If you live in a warm climate, try straight 40W.
Some autopart stores will see what the Check Engine light is on for for free. Since you’ll be buying your oil in bulk, it wouldn’t hurt to ask next time you’re in Auto Zone.
My guess is gas cap. The difference in pressure between a warm day and chilly morning sometimes loosens my gas cap.
Check Engine lights are lit when a problem occurs for a certain number of start/driving cycles and may turn themselves back off when the problem doesn’t occur for a number of cycles. It isn’t a electrical short that is turning it on and off, it is a recurring intermitant problem and will probably tell you where the oil is going when you have it read. There will be a code stored when the light is lit.
Most auto parts stores, like NAPA and AutoZone, will plug a tool into your car and read the code for you and tell you what it might indicate, for free. Sure they will try to sell you something but they won’t make you. Have this done the next time the light comes on. If the light isn’t on there may not be a code stored, wait until it is on.
Get the code read and then you can find out what it means and decide if you want to fix it. Might point you to something relatively cheap that you can have someone replace without putting it in “The Shop”.
